CD4 and brain infarction: Activations of both CD4+ T cells and CD8+ T cells are suppressed by immune checkpoint pathways as a homeostatic mechanism in the atherosclerotic lesions, but, immune checkpoint blockade invigorates T-cell functions and activates APCs, also suggesting a potential risk of triggering disorders of coagulation-fibrinolysis system in arteriosclerotic lesions such as ACS and cerebral infarction in association with ICI therapy (Figure 6B).